Apparatus for straightening the leads of dual in-line packages

ABSTRACT

Two movable members are selectable positioned to form a passageway for handling dual in-line packages. A wheel, comprising resilient material, and a spreader member are selectable positioned in correspondence with the movable members to engage the leads on either side of the package and vertically straighten them. Lateral straightness of the leads, as well as various other package anomalies, are detected by optical scanning.

BACKGROUND OF THE INVENTION

Dual in-line packages are widely used to package integrated circuits,various other electronic devices and combinations thereof. As the volumeof usage has increased over the years, so have the number of packagetypes produced. For example, these are plastic, ceramic, "Cerdip" andside-brazed packages, to name a few. Also, the package length variesfrom as few as four leads to as many as 64 and above per package. Thewidth of the package typically varies between 3/10ths and 6/10ths of aninch. The most standard parameter is that of the lead spacing on eachside of the package which has been fairly consistently held to 0.100inches center-to-center.

Increasingly, there have been efforts to automate the operationsinvolved with these dual in-line packages. For example, the initialtesting and screening of the packages, and the insertion of the packagesinto printed circuit boards through the use of automatic insertionequipment. However, variations in the different package types, asdescribed above, and the fact that individual packages in any given lotwill suffer from physical deformities, hamper the manufacturer and theuser from maximizing the effectiveness of this automatic handlingequipment. For example, individual packages may be malformed or havebent leads which cause the automatic handling equipment to jam.

Previous solutions to these problems have included visual inspection andcorrection of deformities by the operator. Other solutions have includeddesigning passageways of the handling apparatus with looser tolerancesor more forgiving mechanisms. A great deal of effort has been directedtowards the design of apparatus for handling the devices, for screeningdevices to detect anomalies in package dimensions and bent leads, andfor preforming the leads of the devices to the required tolerancesbefore they are placed in subsequent handling equipment. For example,see U.S. Pat. No. 3,727,757 issued to Claude M. Boissicat on Apr. 17,1973 and entitled "DIP Handling Apparatus".

These prior art devices have typically been limited to a single packagewidth and the mechanism would therefore be replaced for each width,e.g., 0.300 inch, 0.400 inch, 0.600 inch, etc. This is an inherentdisadvantage in the increased cost and low utilization of capitalequipment for the manufacturer or user who uses a wide variety ofpackage types. Many of these devices jam or otherwise become inoperativefrom the very problems for which they are screening and therefore theyare not effective outside a fairly small range of package deformities.Also, some prior art lead straighteners and screening equipment haveinvolved techniques such as forcing the package through a formingstructure or otherwise stressing the package to force the leads to thedesired dimensions. This kind of physical stressing of the package mayactually create worse problems than it solves because this physicalstressing of the package may destroy the physical integrity of thepackage, resulting in such undesirable features as a loss ofhermiticity.

SUMMARY OF THE INVENTION

In accordance with the preferred embodiment of the present invention,handling apparatus for dual in-line packages and the like is provided,which comprises two parallel movable members which may be selectablypositioned to provide a passageway of varying width. The passageway thusformed is designed to receive dual in-line packages on their backs withthe leads positioned up in the air. A wheel comprising a resilientmaterial and a spreader member engage the package leads and form them toa preselected lead separation distance. Furthermore, optical scanningapparatus is provided for detecting other physical anomalies in thepackage width and leads such as unacceptable variations in packageheights or the lead spacings which significantly vary from the 0.100inch standard. The optical scanning apparatus may also be adjusted todetect a number of other physical anomalies. Acceptable and unacceptablepackages are then sorted into their respective containers. The handlingapparatus thus constructed is capable of handling packages of varyingwidths and of forming leads within a wide range through simpleadjustments. Furthermore, the apparatus is operable on a continuousbasis and there is no need to "singulate" or provide reservoirs for thepackages during these operations.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is an end view of a typical dual in-line package.

FIG. 2 is a side view of a typical dual in-line package.

FIG. 3 is a top view of a typical dual in-line package.

FIG. 4 is a perspective view of the preferred embodiment.

FIG. 5 illustrates the lead forming apparatus utilized in the preferredembodiment.

FIG. 6 is a cross-sectional view of FIG. 5 and shows the relationship ofthe resilient wheel and the spreader member of the preferred embodimentwith respect to a dual in-line package in the passageway of thepreferred embodiment.

FIG. 7 is a top view of the lead forming assembly of the preferredembodiment.

FIG. 8 is a cross-sectional view of FIG. 7 and shows the structure usedto adjust the separation distance of the movable members and the leadforming apparatus.

FIG. 9 is a block diagram of the optical scanning circuitry of thepreferred embodiment.

FIG. 10 is a timing diagram of the optical scanning circuitry of thepreferred embodiment.

FIG. 11 shows the relationship of FIGS. 11A and 11B.

FIGS. 11A and 11B taken together are a schematic diagram of the opticalscanning circuitry of the preferred embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1, 2 and 3 there is shown a dual in-line package 1050typical of those in use in industry today. These packages typicallycomprise a body 15 and a plurality of legs 20. Besides variations inpackage thickness 21, different package types and even the same typesupplied by different manufacturers will vary in the angle 30 betweenthe legs and the body and the distance 35 between the legs on therespective sides of the packages. The angle 30 between the legs and thepackage is dependent on the type of package, the manufacturingtechniques and package specifications of the particular manufacturer.Distance 35 is nominally a standard distance such as 0.300, 0.400, or0.600 inches. Various factors such as the tolerances applied to thesedistances and, of course, individual package deformities caused byhandling and shipping, etc., will operate to cause distance 35 to beeither greater or smaller than acceptable limits. When lead spacing on apackage exceeds or falls below these limits, it becomes difficult toinsert in a printed circuit (PC) board and will cause jams in automatichandling equipment.

In FIG. 1 it can be seen that lead 22 has been bent outward from thepackage and has hence exceeded the acceptable tolerances within thestandard distance, while lead 24 has been bent inward to a point whereit falls below the acceptable tolerances for distance 35. In the ensuingdiscussion of the preferred embodiment, this type of deformity will bereferred to as longitudinal straightness or the lack thereof.

In FIG. 2 a side view of the dual in-line package is shown. Note thatthe majority of legs 20 are spaced apart at uniform distance 42.However, note that leg 45 has been deformed, i.e., it is bent sidewards.This type of deformity also causes a problem when attempts are made toinsert the device in a printed circuit board. However, studies haveshown that by far the greatest problem is a deformity as shown inFIG. 1. Hence, the dual in-line package handling apparatus of thepreferred embodiment will correct for longitudinal straightness to bringall the legs 20 into alignment at approximately nominal distance 35.Optical scanning apparatus is then provided to detect lateralstraightness problems such as shown in FIG. 2. These devices which lackstraightness are then sorted into a separate container to bestraightened at a later time.

In FIG. 4 there is shown a perspective view of the preferred embodiment.Packages to be formed are inserted at opening 905. The width of thepassageway 910 formed by movable members 40 and 45 may be adjusted toaccommodate the desired package width by adjustment 65. The desired leadspread may be independently varied by adjustment 66. In the preferredembodiment, adjustment 65 controls the passageway width while adjustment66 controls the lead spacing widths, i.e., distance 35 per FIG. 1, towhich lead forming assemblies 41 and 43 will form the leads of thepackages fed through passageway 910. The operation of lead formingassemblies 41 and 43 is described in more detail with respect to FIGS.5, 6, 7 and 8. Indicators 410 and 415 are provided to display thedistances set by adjustments 66 and 65, respectively.

After lead forming apparatus 41 and 43 have formed the leads of thepackage to the distance preselected by lead spread adjustment 66, theleads now being formed longitudinally straight after this operation, thepackage proceeds down passageway 910 and is then engaged by a belt 930.

Belt 930 is provided to insure a more constant velocity as the packagesproceed past optical-scanning units contained in assemblies 940 and 950.(Belt 930 is driven by a constant velocity motor.) Each side is scannedby a separate scanning unit, such as scanning unit 942. This unit andthe associated electronic circuitry described in more detail withrespect to FIGS. 9, 10 and 11 determine whether the lateral spacing oneach side of the package is within the selectably programmed tolerances.The acceptable and reject packages are then directed to their respectivecontainers by flipper 956 in response to a control signal from thescanning apparatus. Therefore, only those packages which are rejectedneed be passed through apparatus for correcting improper lateral leadspacing. Since this apparatus is inherently more expensive and slower inoperation, significant economies can be realized by only performinglateral straightening operations on those devices which actually requirethem.

Referring now to FIG. 5, there is shown the lead forming apparatus ofthe preferred embodiment. Dual in-line packages such as package 1050travel down the passageway formed by movable members 40 and 45. Thesepackages may have leads which are bent longitudinally, such as leads1051 and 1052, respectively. Assuming that it is desired to bend leadsinto alignment along line 1012, a wheel 1010, having an O-ring 1115 ofresilient material positioned about the circumference thereof, isutilized to first bend all the leads inwards to the approximate positionof line 1013 and a spreader member 1030 is utilized to bend the leadsoutwards to the approximate position of line 1011. This is necessarybecause of the spring-back or memory characteristics of the leadmaterial. (In the preferred embodiment this spring-back distance isapproximately equal to the distance from line 1012 to either line 1011or 1013.) For example, lead 1051, which is bent outwards, must beoverbent to the approximate position of line 1013 in order that it willbe in line with line 1012 after it has sprung back after completion ofthe forming operation. To form all leads properly, the leads are firstengaged by the wheel 1010 somewhere between points 1015 and 1016 andbent inwards in line with line 1013. If these leads were then released,the spring-back quality of the lead material causes them to line up withline 1012. However, this will only occur if the leads were in-linealready or were bent outwards, such as lead 1053 or lead 1051,respectively. For leads which are bent inwards, such as lead 1052, it isnecessary to bend the leads outwards in line with line 1011 so that theywill then spring back in-line with line 1012. Therefore, after the leadshave been engaged by resilient wheel 1010, and bent inwards to theapproximate position of line 1013. They are then engaged by spreader bar1030 and forced outwards into approximate alignment with line 1011. Thedisengagement point from wheel 1010 and spreader bar 1030 is thetangential meeting of wheel 1010 and spreader bar 1030 at a point 1026which has been designed in the preferred embodiment to be in line withline 1011. Obviously, the corresponding operations are performed on theleads extending from the other side of the device by wheel 1041 andspreader bar 1020. In this way, the leads are formed to the distance1025 which has been set by adjustment 66.

In the preferred embodiment the resilient portion of wheels 1010 and1041 comprises O-rings 1115 and 1116, as shown in the cross-sectionalview of FIG. 6, which are positioned in circumferential grooves in thebody of wheels 1010 and 1041. If prolonged usage of the lead formingapparatus results in severe abrasion of the resilient surface, theO-ring may be replaced. Similarly, a replaceable insert 1130 is providedin base 47.

Referring now to FIG. 8, there is shown the passageway used in thepreferred embodiment. The dual in-line packages are handled in anessentially upside down position. Therefore, deformities in the lateraland longitudinal straightness of the leads present minimal obstructionto the progress of the package through the passageway. In contrast tothe prior art, the passageway of the preferred embodiment is adjustableto accommodate various package widths, i.e., movable members 40 and 45are not limited to a single passageway width. Other dual in-linepackages handling apparatus may be coupled to or mounted upon thesemovable members 40 and 45 and the distance therebetween may also beindependently adjusted to accommodate other package parameters oroperations thereon.

In the cross-sectional views of FIG. 6 and FIG. 8, it can be seen thatthe passageway of the preferred embodiment is formed by movable members40 and 45 and base 47. Movable members 40 and 45 are adjusted toaccommodate the width of a particular package 1050. This is accomplishedby the rotation of threaded shaft 1105. The lower portion of movablemember 40 rides upon a portion of threaded shaft 1105 havingright-handed threads while the lower portion of movable member 45 rideson a portion of threaded shaft 1105 which has left-handed threads. (InFIG. 8, threaded portions 1120 and 1107 of threaded shafts 1106 and1105, respectively, are right-handed threads while threaded portions1119 and 1108 are left-handed threads.) Since the screw threads drivingmovable members 40 and 45 are opposite in direction, movable members 40and 45 either move towards or move away from each other in response tothe turning of shaft 1105. Note that this technique of adjusting thepassageway width also has the advantage that the movable membersmaintain a common centerline no matter what package width is selected.This allows elements not mounted on movable members 40 and 45, such asflipper 956, to also maintain proper spatial relationship for thepackage width selected.

Bearing supports 1110, 1111, and 1112 are provided to restrict threadedshaft 1105 to purely rotational movement as much as possible. When shaft1105 is rotated, it not only moves movable members 40 and 45 but alsomoves the lead forming assemblies comprising wheels 1010 and 1041 andspreader members 1020 and 1030.

However, the lead forming assemblies are capable of further adjustment(without interfering with the spatial relationship of movable members 40and 45) through adjustment 66 which controls the rotation of a shaft1106. The turning of shaft 1106 moves the lead forming assemblies closertogether or further apart depending on the direction of rotation.Furthermore, note that a slip clutch 1118 is provided in threaded shaft1106 to allow the distance between the lead forming assemblies to beadjusted independently of the positioning of movable members 40 and 45.

Referring now to FIG. 9, there is shown a block diagram of the opticalscanning circuitry of the preferred embodiment. Lead spacing on bothsides of the package is checked simultaneously by left scanner 942 andright scanner 952, respectively. Any high quality optical scanner, suchas those manufactured by the Skan-a-matic Corporation, may be used todetect the presence of each lead. In the preferred embodiment, a fiberoptic scanner is used, Model S 3010-3 of the Skan-a-matic Corporation.The scanner produces an output signal whenever light transmitted by thescanner is returned by a reflecting surface passing thereby. In thepreferred embodiment, these reflecting surfaces are the leads of thedual in-line package. The reflected light is sensed by a phototransistor in scanners 942 and 952. The output signal of the scanner isamplified by sense amplifiers 1510 and 1515. The signals from senseamplifiers 1510 and 1515 are sent to Schmitt triggers 1520 and 1525 forpulse shaping. When the first lead of the package is sensed, OR-gate1530 produces an output on a line 1531. The signal on line 1531 causesoscillator 1540 and window circuit 1550 to produce an output signal online 1551. The waveform of this signal is shown on line A of FIG. 10.Negative going pulses are produced at a time interval approximatelyequal to the time interval that each successive lead should pass thescanner if the leads are properly spaced. The selection of this timeinterval is based upon the distance between the leads, the tolerancesselected and upon the approximate velocity of the device as it passesthe scanner. Note that the belt 930 as described with respect to FIG. 4helps to insure that the device will move past the scanners at a nearconstant velocity.

In the preferred embodiment, the first lead sensed is assumed to bedirectly on center and therefore the first time interval provided isequal to 0.095 inches divided by the approximate speed of the devicepast the scanner. Thereafter, each time interval is equal to 0.100inches divided by the approximate speed of the device past the scanner.The width of the pulses generated by window circuit 1550 determines thedeviation from the exact distance of 0.100 inches that will betolerated. For example, time interval 1618 represents the minimum timeinterval that will be acceptable between the sensing of adjacent leads,while time interval 1622 indicates the maximum time interval that willbe accepted by the scanning circuitry. Time interval 1618 and 1622correspond to the minimum and maximum inter-lead spacing acceptable forthe particular application. Note that the signal on line 1551 isutilized by both comparator 1560 and comparator 1565 to determinewhether the signals produced on lines 1521 and 1526 by the scanningapparatus as the leads pass by the scanner are within the acceptabletolerances. In this way not only are the interlead spacings on each sideof the package checked for correct spacing but also the alignment of oneside to the other must be within the accepted tolerances. If any one ofthe leads on either side of the package is not within acceptable limits,OR-gate 1570 will trigger reject flip-flop 1575. When this occurs,flipper 956 is activated and the device is guided into the rejectcontainer.

Referring now to FIGS. 11A and 11B, there is shown a detailed schematicdiagram of the optical scanning circuitry of the preferred embodiment.When the leads are detected by optical scanners 942 and 952, theyactivate sense amplifiers 1510 and 1515 and Schmitt triggers 1520 and1526, respectively. The first lead to be sensed produces an outputsignal on line 1521 and 1526 and thereby causes OR-gate 1530 to triggeroscillator 1540. Oscillator 1540 then causes window circuit 1550 tooutput a train of pulses, the number of said pulses corresponding to thenumber of leads on each side of the package. The number of leads on eachpackage has been preset into counters 1750 and 1755 via switches 1760and 1765. The width of the pulses produced is determined by thetolerance which has been selected and input to counters 1730 and 1735via switches 1740 and 1745. Each time a window pulse is produced, thesignal on line 1551 causes counters 1750 and 1755 to count down by one.When the zero count is reached, counter 1755 generates a clear signal ona line 1756 which presets reject flip-flop 1575, as well as variousother circuitry in the preferred embodiment.

For the purposes of explanation, we will assume that the left scannerdetector 942 has sensed a first lead. Light from the lamp insde thescanner is reflected and actuates photo-transistor 1502.Photo-transistor 1502 turns on and causes the input of transistor 1504to go low. (Transistor 1504 is similar to the SD 211 manufactured bySignetics Corporation and others.) This causes a high output signal tothe input to Schmitt trigger 1520. The output signal on line 1521 isproduced, which activates OR-gate 1530. Note that the signal on line1521 is also coupled to the clock input of flip-flop 1560, but this hasno effect as the direct clear input is being held low, which disablesthis flip-flop. the low going output from OR-gate 1530 is capacitivelycoupled to flip-flops 1732 and 1728. Flip-flop 1732 enables theoscillator circuit 1540. The oscillator circuit 1540 output signal online 1734 is the input to divide-by-16 counter 1736. The output ofdivide-by-16 counter 1736 is coupled to gate 1729 and, through gate1729, to counters 1730 and 1735. Counters 1730 and 1735 control the timebetween the detection of the first lead and the start of the succeedingwindow pulse produced on line 1551. After the first window, counters1730 and 1735 will count a full 100 count for each lead of the package.The number set in switches 1740 and 1745 are assumed to be in thousandsof inches and represent the tolerance from the 0.100 inch standardspacing. This cycling for the full 100 count will continue until latch1728 is reset, which indicates the last lead has been scanned.

Counters 1752 and 1754 are also preset to the value in switches 1740 and1745. Counters 1752 and 1754 control the pulse width of the signalproduced on line 1551. For example, if a tolerance of 5/1000 inch is setinto thumb wheel switches 1740 and 1745, counters 1730 and 1735 willcount from a set of 5 to a 100 count, which would yield a total countequivalent to 95, indicating a time interval which represents a distanceof 95/1000 inch in the preferred embodiment. As that time a low pulsefrom counter 1735 sets latch 1549 and commences the generation of thewindow pulse on line 1551. Simultaneously, down-counters 1752 and 1754start counting down from the pre-set value of 5. At the completion ofthis count-down, counter 1754 outputs a negative going signal whichcauses flip-flop 1549 to set. This count-down from 5 to 0 is equivalentto counting for 10/1000 inch or a count of 10 because of the divide-by-2effect of flipflop 1728. Hence, a setting of 5 to represent 5/1000 inchinitially represents a plus or minus 5/1000 tolerance and therefore awindow of 10/1000 inches is produced. If the leads are within tolerance,the comparators 1560 and 1565 will be clocked during the negative goingwindow pulses and the package will therefore not be rejected. However,should a lead be out of tolerance, the detection pulses on lines 1521and 1526 will not occur simultaneously with window 1551 and hencecomparators 1560 and 1565 will be set, thereby causing the output ofgate 1570 to set reject flip-flop 1575. The flipper 956 as shown in FIG.4 will then be activated and the rejected package will be guided to theappropriate receptacle. The counters 1760 and 1765 are preset to thenumber of leads contained on each side of the package. As a window pulseis generated on line 1551, it causes the counters 1760 and 1765 to countdown. When the counters 1760 and 1765 reach a zero count, indicatingthat all the leads on the package have been scanned, a clear signal willbe generated, presetting various internal circuitry such as rejectflip-flop 1575.

We claim:
 1. Apparatus for straightening lead tips of a moving DualIn-Line Packaged (DIP) electronics device having a body and leads withshoulder and tip portions comprising:guiding means having membersforming a channel disposed to receive a DIP device having lead tipsoriented in a generally upward position for guiding the body of the DIPdevice along a path as it moves by applying biasing force to theshoulder portions of the leads; a pair of wheels disposed about the pathfor engaging the lead tips of a DIP device moving along the path andbending the lead tips toward the center of the path as the DIP devicemoves along the path; and biasing means disposed along the path forbending the lead tips of a DIP device away from the center of the pathby applying a bias force to the tips as the DIP device moves along thepath.
 2. Apparatus as in claim 1 wherein the members are movable forvarying dimensions of the path to accommodate different body dimensions.3. Apparatus as in claim 2 wherein said pair of wheels comprise a firstand second wheel each having a resilient portion about the peripherythereof.
 4. Apparatus as in claim 2 wherein biasing means comprise afirst platen having a surface disposed in tangential relationship withthe periphery of the first wheel and oriented at an angle with referenceto said path.
 5. Apparatus as in claim 4 wherein the periphery of saidfirst wheel forms a radiused surface at the point where the surface ofthe first platen is in tangential relationship with the first wheel forforming a radiused pivot point for bending the lead tips.
 6. Apparatusas in claim 4 wherein the positions of the first platen and the firstwheel are movable with reference to said path.
 7. Apparatus forstraightening lead tips of a moving device having a generallyrectangularly shaped body with a plurality of lead tips extendingtherefrom in a substantially linear array comprising:guiding meanshaving members forming a channel disposed to receive a device havinglead tips in a generally upward position for guiding the body of thedevice along a path as it moves; a wheel disposed about the path forengaging the lead tips of a device moving along the path and bending thelead tips toward the center of the path as the device moves; and biasingmeans disposed along the path for bending the lead tips of a device awayfrom the center of the path by applying a bias force to the tips as thedevice moves along the path.
 8. Apparatus as in claim 7 wherein themembers are movable for varying dimensions of the path to accomodatedifferent body dimensions.
 9. Apparatus as in claim 7 wherein the wheelhas a resilient portion about its periphery.
 10. Apparatus as in claim 7wherein biasing means comprise a platen having a surface disposed intangential relationship with the periphery of the wheel and oriented atan angle with reference to said path.
 11. Apparatus as in claim 10wherein the periphery of the wheel forms a radiused surface at the pointwhere the surface of the platen is in tangential relationship with thewheel for forming a radiused pivot point for bending the lead tips. 12.Apparatus as in claim 10 wherein the positions of the platen and thewheel are movable with reference to said path.